Why Siemens touch screen display CPU unresponsive

1 in the touch screen is not set CPU address, touch screen address and communication speed correctly connected (Note to the CPU in the same) 2 across the network station address duplicate 3 CPU is not powered 4 cable connection 5 is not guaranteed The total length of a segment within 50 m, total number of stations within 32 6 electromagnetic interference touch screen models: 6AV6640-0AA00-0AX0, Kunshan RWD Special supply genuine original spot